Stems in ι and υ are of two kinds:—
1. a. Stems in ι, with genitive in -εως, as (masc.) μάντις
b. Stems in ι, with genitive in -ιος, as ὁ κί_ς
2. a. Stems in υ, with genitive in -υος; as (masc.) μῦς
b. Stems in υ, with genitive in -εως: (masc.) πῆχυς
N. 1.—In the nom., acc., and voc. sing. barytone stems in υ have short υ; oxytone substantives (usually) and monosyllables have υ_; and monosyllables circumflex the υ_ (σῦς, σῦν, σῦ).
N. 2.—ἡ ἔγχελυς
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].